ListPreferenceMultiSelect.java

/**
 * Copyright 2010 Eric Taix
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and 
 * limitations under the License.
 * 
 */
package com.bigpupdev.synodroid.preference;

import android.app.AlertDialog.Builder;
import android.content.Context;
import android.content.DialogInterface;
import android.preference.ListPreference;
import android.util.AttributeSet;

/**
 * A Preference that displays a list of entries as a dialog and allows multiple selections
 * <p>
 * This preference will store a string into the SharedPreferences. This string will be the values selected from the {@link #setEntryValues(CharSequence[])} array.
 * </p>
 */
public class ListPreferenceMultiSelect extends ListPreference {
	// Need to make sure the SEPARATOR is unique and weird enough that it doesn't
	// match one of the entries.
	// Not using any fancy symbols because this is interpreted as a regex for
	// splitting strings.
	private static final String SEPARATOR = "OV=I=XseparatorX=I=VO";

	private boolean[] mClickedDialogEntryIndices;

	public ListPreferenceMultiSelect(Context context, AttributeSet attrs) {
		super(context, attrs);
	}

	@Override
	public void setEntries(CharSequence[] entries) {
		super.setEntries(entries);
		mClickedDialogEntryIndices = new boolean[entries.length];
	}

	public ListPreferenceMultiSelect(Context context) {
		this(context, null);
	}

	@Override
	protected void onPrepareDialogBuilder(Builder builder) {
		CharSequence[] entries = getEntries();
		CharSequence[] entryValues = getEntryValues();

		if (entries == null || entryValues == null || entries.length != entryValues.length) {
			throw new IllegalStateException("ListPreference requires an entries array and an entryValues array which are both the same length");
		}

		restoreCheckedEntries();
		builder.setMultiChoiceItems(entries, mClickedDialogEntryIndices, new DialogInterface.OnMultiChoiceClickListener() {
			public void onClick(DialogInterface dialog, int which, boolean val) {
				mClickedDialogEntryIndices[which] = val;
			}
		});
	}

	/**
	 * Parse a string which contains values separate by separator and returns a string array
	 * 
	 * @param val
	 * @return
	 */
	public static String[] parseStoredValue(CharSequence val) {
		if ("".equals(val))
			return null;
		else
			try {
				return ((String) val).split(SEPARATOR);
			} catch (Exception e) {
				return null;
			}

	}

	/**
	 * Restore checked entries according to the current value
	 */
	private void restoreCheckedEntries() {
		CharSequence[] entryValues = getEntryValues();
		String[] vals = parseStoredValue(getValue());
		if (vals != null) {
			for (int j = 0; j < vals.length; j++) {
				String val = vals[j].trim();
				for (int i = 0; i < entryValues.length; i++) {
					CharSequence entry = entryValues[i];
					if (entry.equals(val)) {
						mClickedDialogEntryIndices[i] = true;
						break;
					}
				}
			}
		}
	}

	@Override
	protected void onDialogClosed(boolean positiveResult) {
		CharSequence[] entryValues = getEntryValues();
		if (positiveResult && entryValues != null) {
			StringBuffer value = new StringBuffer();
			for (int i = 0; i < entryValues.length; i++) {
				if (mClickedDialogEntryIndices[i]) {
					value.append(entryValues[i]).append(SEPARATOR);
				}
			}

			if (callChangeListener(value)) {
				String val = value.toString();
				if (val.length() > 0)
					val = val.substring(0, val.length() - SEPARATOR.length());
				setValue(val);
			}
		}
	}
}